Home Secretary Theresa May says the UK is facing a terror threat "perhaps greater than it has ever been", and this week's anti-terrorism bill includes tighter airport security. But two psychology professors say current screening methods used at airports, where security agents check the behaviour of passengers for "suspicious signs", need an urgent upgrade.

If you have extremely suspicious thoughts, or you hear voices that other people can't hear, traditionally these are seen as signs of a serious mental illness such as schizophrenia. On Thursday this week a major new report from the British Psychological Society will call for a radical change in the way we think and offer help to people who are experiencing psychosis. Claudia Hammond discusses how our knowledge, attitudes and treatment of psychosis and schizophrenia have changed over the past decade with anti-stigma campaigner for Time to Change, Nikki Mattocks, author of "Eyebrows and Other Fish", Anthony Scally, consultant psychiatrist Dr Shubulade Smith and BPS Report Editor, clinical psychologist Anne Cooke.

Thirty years ago psychologists found that if people were instructed to open their mouths in a smile, their mood improved...even though they didn't know they were smiling. When we feel happy, we smile, and the brain gets so used to this that it seems to happen the other way round too. Now new research suggests the same thing could happen when we walk. Johannes Michalak from Witten Herdecke University in Germany, found that when people were trained to walk in a happy style, their memories became more positive.

Producer: Fiona Hill.